Method for controlling a radio access bearer in a communication system

ABSTRACT

A radio access bearer in a mobile communication system is controlled by disposing a radio resource control layer having radio access bearers in a user side, disposing a radio link control layer, a media access control layer, and a physical layer in the user side beneath the radio resource control layer in succession, measuring a traffic volume of the media access control layer and radio link control layer in the user side by using the media access control layer in the user side to produce traffic volume measurements, comparing the traffic volume measurements to at least one of an upper critical value and a lower critical value provided to the media access control layer in the user side from a radio resource control layer in a network side of the communication system through the radio resource control layer in the user side of the system, and forwarding a comparison result and the traffic volume measurements to the radio resource control layer in the network side through the radio resource control layer in the user side, and controlling the radio access bearer in the user side through the radio resource control layer in the network side according to a result of the comparison.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority from Korean Patent Application No. P1999-26688 filed on Jul. 2, 1999, the entirety of which is hereby incorporated by reference for all purposes as if fully set forth therein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a next generation mobile communication system, and more particularly, to in a method for controlling a radio access bearer in a next generation mobile communication system.

2. Background of the Related Art

Recently, the Association of Radio Industries and Business (ARIB) in Japan, the European Telecommunications Standards Institute (ETSI) in Europe, the TI in the USA, the Telecommunications Technology Association (TTA) in Korea, and the TTC in Japan have planned a further evolved next generation mobile communication system based both on the core network technology of the existing Global System for Mobile Communications (GSM) which serves for multimedia, such as audio, video and data, and radio access technology. These organizations have agreed on common research for suggesting a technical specification for the evolved next generation mobile communication system, a project named Third Generation Partnership Project (3GPP). The 3GPP encompasses the following three technical research fields.

The first technical research field is the 3GPP system and service field, for researching system architectures and service capabilities based on the 3GPP specification.

The second technical research field is the field of Universal Terrestrial Radio Access Network (UTRAN). The UTRAN is a RAN (Radio Access Network), including W-CDMA according to a Frequency Division Duplex (FDD) mode, and TD-CDMA according to a Time Division Duplex (TDD) mode.

The third technical research field pertains to a core network having a third generation networking capability, such as mobility management and global roaming, being evolved from the second generation GSM.

Of the Technical Specification Groups (TSGs) conducting such technical research, the Working Group 1 (WG1) related to Radio Access Networks (RAN) suggests general technologies for the physical layer (Layer 1), and the Working Group 2 (WG2), defines a data link layer (Layer 2) and a network layer (Layer 3), both being at higher levels than the physical layer, as a second radio layer (Radio Layer 2) and a third radio layer (Radio Layer 3), and suggests general technologies on the second and third radio layers.

FIG. 1 illustrates a related art radio interface protocol architecture according to the 3GPP RAN. An air-interface protocol between UE (User Equipment) and a network side (UMTS Terrestrial Radio Access Network, UTRAN) consists of layer 1, radio layer 2, and radio layer 3.

Referring to FIG. 1, a protocol architecture is divided into a control plane (C-Plane) for signaling, and a user plane (U-Plane) for transmission of information. The C-Plane has a Radio Resource Control (RRC) Layer at Layer 3, and a Radio Link Control (RLC) Layer and a Medium Access Control (MAC) Layer at Layer 2, a layer lower than the Layer 3, and a Layer 1 at a lowest layer. The U-Plane has the RLC and MAC at Layer 2, and the Layer 1, a layer lower than the Layer 2. The Layer 1 provides a transport channel for upper layer(s) inclusive of the MAC. In this instance, depending on how information is transferred on the air-interface, different transport channels are provided, i.e., either a common transport channel or a dedicated transport channel is provided.

The MAC provides the upper RLC with logical channels, which differ depending on the forms of information to be transported. That is, the MAC provides the data transfer service on the logical channels, forms of which logical channels differ depending on the kinds of the data transfer services provided by the MAC. In this instance, the forms of the logical channels differ depending on the forms of information to be transported, wherein, in general, control channels are provided when information for the C-Plane is to be transported, and traffic channels are provided when information for the U-Plane is to be transported. Besides this, the MAC provides radio resource reconfiguration and MAC parameter reconfiguration services, which are served when the RRC requests a radio resource reconfiguration or a MAC parameter change. The MAC also provides a measurement report service, reporting traffic volume values, a service quality index, a MAC condition index, and the like to the RRC. The MAC providing those services has many functions, including a traffic volume monitoring function which informs the RRC of the traffic volume on the logical channel. The RRC analyses traffic volume information reported from the MAC, and determines switching for the transport channels.

The RLC provides services for radio access establishment/or cancelation. The RLC also provides a service for transporting PDU (Protocol Data Units) at the upper layer to which any protocol information, inclusive of segmentation/reassembly functions, is not included. The RRC provides an information broadcast service, in which information is broadcast to all UE in an one area. The RRC also controls Layer 3 C-Plane signal processing between the UE and the UTRAN. That is, the RRC provides functions of establishment, sustenance, and cancelation of radio resource access between the UE and the UTRAN. Particularly, the RRC provides functions of establishment, sustenance, or cancelation of radio access bearers, functions of assignment, reconfiguration, and cancelation of radio resources required for radio resource access (the bearer is a capability defined for a signal transfer on the radio interface), and UE measurement report and report control functions, corresponding to the traffic volume monitoring function among the functions of the MAC. The measurements at the UE are controlled by the RRC, when the RRC informs the UE of an object, a time and a method of the measurement. Then, the RRC informs the UTRAN of the measurements at the UE. The radio interface protocol layers explained up to now provide other various functions and services. In such an existing radio interface protocol architecture, traffic volume at the RLC is monitored at the MAC in the U-Plane, for the RRC to assign, sustain or cancel radio resources.

However, no detailed procedures for these functions are suggested yet, in fact. That is, as explained, what is described in the 3GPP RAN is only that a RLC traffic volume in a current user system is monitored at the MAC, and only that radio access bearer control procedures, such as bearer reconfiguration, and channel reconfiguration are carried out according to the traffic volume monitoring at the MAC, without any suggestions for detailed procedures for carrying this out.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method for controlling a radio access bearer in a mobile communication system that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

An object of the present invention is to provide a method for controlling a radio access bearer in a mobile communication system, for controlling a radio bearer according to traffic volume more accurately.

Another object of the present invention is to provide a method for controlling a radio access bearer in a mobile communication system, for efficient management of radio resources according to traffic volume in a radio interface protocol.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposes of the present invention, as embodied and broadly described, a method for controlling a radio access bearer in a mobile communication system, comprising: (1) disposing a radio resource control layer having radio access bearers in a user side of the communication system; (2) disposing a radio link control layer, a media access control layer, and a physical layer in the user side beneath the radio resource control layer in succession; (3) measuring a traffic volume of the media access control layer and radio link control layer in the user side by using the media access control layer in the user side to produce traffic volume measurements; (4) comparing the traffic volume measurements to at least one of an upper critical value and a lower critical value provided to the media access control layer in the user side from a radio resource control layer in a network side of the communication system through the radio resource control layer in the user side of the system, and forwarding a comparison result and the traffic volume measurements to the radio resource control layer in the network side through the radio resource control layer in the user side; and (5) controlling the radio access bearer in the user side through the radio resource control layer in the network side according to a result of the comparison.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

In the drawings:

FIG. 1 illustrates a diagram showing a related art radio interface protocol architecture according to the 3GPP RAN;

FIG. 2 illustrates a diagram showing a system of protocol entities for explaining a procedure for controlling an active radio access bearer in accordance with a preferred embodiment of the present invention;

FIG. 3 illustrates a diagram showing a procedure for monitoring traffic volume for controlling an active radio access bearer in accordance with a preferred embodiment of the present invention;

FIGS. 4A-4C illustrate states of buffers in protocol entities for controlling an active radio access bearer in accordance with a preferred embodiment of the present invention;

FIG. 5 illustrates another system of protocol entities explaining a procedure for controlling an active radio access bearer in accordance with a preferred embodiment of the present invention; and,

FIG. 6 illustrates a flow chart showing a process for monitoring traffic volume for controlling an active radio access bearer in accordance with a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. FIG. 2 illustrates a diagram showing a system of protocol entities for explaining a procedure for controlling an active radio access bearer in accordance with a preferred embodiment of the present invention, particularly, a state before a transport channel is switched in conducting traffic volume monitoring, and an initial state of the MAC. The MAC is disposed by the RRC including radio access bearers RAB1, RAB2 and RAB3 multiplexed into dedicated channels DCH1, and DCH2. The dedicated channels DCH1 are DCH2 are multiplexed into a Coded Composite Transport Channel (CCTrCH). After disposing the radio access bearers, the RRC disposes the lower three layers of the RLC, tkdr1, and MAC, and the physical layer (hereafter called as “PHY”). When these lower three layers are disposed, the RRC provides a disposal request primitive CMAC_configure_REQ to the MAC, which includes: first, radio access bearer identification (ID), second, a logical channel ID, which is multiplexing information, a transport channel ID, and a logical format priority according to a service quality (QoS), and third, a transport format combination set, which is transport channel information. Upon completion of disposal of the lower three layers, the RRC requests the MAC to carry out a traffic volume monitoring function.

FIG. 3 illustrates a flow of messages showing a procedure for monitoring traffic volume in accordance with a preferred embodiment of the present invention.

Referring to FIG. 3, before the process for monitoring traffic volume, the UTRAN-RRC provides a system information message to the UE-RRC through a BCCH (Broadcasting Control Channel) (S1), and a MEASUREMENT CONTROL message through a Digital Control Channel (DCCH). (S2). Eventually, the UE-RRC can have parameters required for the traffic volume measurement. Then, the UE-RRC requests the UE-MAC to carry out the traffic volume monitoring (S3). In this instance, the UE-RRC provides the UE-MAC with a primitive CMAC_MEASUREMENT_REQ, containing a measurement report mode parameter, and a measurement period parameter. If the measurement report mode is a periodic mode, a report interval parameter is added thereto, and if the measurement report mode is an event trigger mode, an upper critical value TH_(U) parameter and a lower critical value TH_(L) parameter are added thereto. The upper critical value TH_(U) parameter denotes a greatest boundary traffic volume in reporting measurements to UE-MAC, and the lower critical value TH_(L) parameter denotes a smallest boundary traffic volume in reporting measurement to the UE-MAC. Then, the UE-RLC provides the UE-MAC with states of respective buffers, and its own data through the primitive RLC_DATA_REQ at fixed intervals (S4). In this instance, as shown in FIG. 2, respective buffers are at transport RLC buffer 1, 2, and 3 states, and data inclusive of the respective buffer states are provided through a dedicated traffic channel (DTCH). If the present measurement report mode is a periodic mode, the UE-MAC receives results of measurements at the transport RLC buffers 1, 2, and 3, and results of measurements at its transport MAC buffers 4, and 5, and provides these to the UE-RRC, periodically. (S5). Conversely, if the present measurement report mode is an event trigger mode, the UE-MAC checks if the results of measurements at the transport RLC buffers 1, 2, and 3, and the results of measurements at its own transport MAC buffers 4, and 5 either exceed the upper critical value TH_(U) or are lower than the critical value TH_(L). If the results are outside the bounds TH_(U) and TH_(L), then they are reported to the UE-RRC (S5).

In the foregoing step S5, the UE-MAC uses the primitive CAMC_MEASUREMENT_IND, together with the following parameters in reporting to UE-PRC. First, a sum of data existing at the transport RLC buffers 1, 2, and 3, and the transport buffers 4, and 5 corresponding to the traffic volume transported through the CCTrCH of the PHY is used. In other words, a sum of data existing at buffers of all transport channels and all data existing at buffers of logical channels, multiplexed by the CCTrCH, is used. The sum of data forms the measurement results reported to the UE-RRC described in the step S5. As other parameters, states of respective buffers the UE-RLC provides to the UE-MAC at every interval through the primitive RLC_DATA_REQ are used. That is, the amounts of data corresponding to respective radio access bearers RAB1, RAB2, and RAB3 are used. In this instance, as statistic values obtained by measuring respective buffer data for a given time period, averages and deviations of amounts of data existing at respective buffers are used. As another parameters, averages and deviations of amounts of traffic transported through respective transport channels, and statistics of measurement of respective channels for a given time period are used.

Then, upon reception of the measurement results on the buffer states from the UE-MAC, the UE-RRC provides the measurement results on the buffer states to the UTRAN-RRC (S6). In this instance, the measurement results are provided through the DCCH, and primitive MEASUREMENT_REPORT_MESSAGE is used.

Finally, the UTRAN-RRC controls the radio access bearer with reference to, or according to, a result of the report of the measurement results.

The radio access bearers may be controlled by bearer reconfiguration, transport channel reconfiguration, physical channel reconfiguration, and TFC (Transport Format Combination) (S7). The bearer reconfiguration is required for correcting transport channels of the RLC, and MAC, and a configuration of the PHY entirely, and the transport channel reconfiguration is required for correcting the transport channel of the MAC and a configuration of the PHY. The physical channel reconfiguration is also required for correcting a configuration of the PHY. Thus, upon completion of the procedure for controlling the radio access bearers, the UTRAN_RRC provides new critical values to the UE-RRC, and the UE-RRC provides the new critical values to the UE-MAC. According to this, the MAC uses the new critical values provided thereto in carrying out the traffic volume monitoring function. By the way, if the received critical value drops below a specific level continuously while the MAC carries out the traffic volume monitoring function continuously and MAC receives the new critical values continuously, the transport channel type is changed from a Dedicated Channel (DCH) to a Random Access Channel (RACH). That is, the form or type of transport channel is switched.

FIGS. 4A-4C illustrate how states of buffers in protocol entities in a traffic volume monitoring process change with time. FIG. 5 illustrates the radio interface protocol architecture after the switching of a transport channel type occurs in the traffic volume monitoring process. From FIG. 5, it can be seen that the PDU (Protocol Data Unit) of the RLC is transported, not through the dedicated MAC (MAC-d), but through a common MAC (MAC-c).

FIG. 6 illustrates a flow chart showing a process for monitoring traffic volume for controlling radio access bearers in accordance with a preferred embodiment of the present invention. In order to make explanation of FIG. 6 clearer, the explanation also will refer to FIGS. 2-5.

First, the MAC is provided with measurement parameters, inclusive of the upper critical value TH_(U) and the lower critical value TH_(L) provided from the RRC (S10). Basically, the MAC is provided with a RLC PDU from each of the RLCs which transports different radio access bearers RAB1, RAB2, and RAB3, and, at the same time, a state of each of the transport RLC buffers 1, 2, and 3 corresponding to respective radio access bearers from the RLC. Then, the MAC measures the a sum of data existing at the transport RLC buffers 1, 2, and 3, and the transport MAC buffers 4, and 5, which corresponds to the traffic volume transported through the CCTrCH (S11). Then, the MAC compares the traffic volume measurement of the channel CCTrCH to the upper critical value TH_(U) and the lower critical value TH_(L) provided from the RRC (S12). If the measured traffic volume of the channel CCTrCH is a value falling between the upper critical value TH_(U) and the lower critical value TH_(L), the traffic volume measurement of the channel CCTrCH is measured at fixed intervals (for example, at every 10 ms). However, if the traffic volume measurement of the channel CCTrCH falls outside of the range between the upper critical value TH_(U) and the lower critical value TH_(L), then the result of the traffic volume measurement of the channel CCTrCH is provided to the RRC (S13). Then, the RRC undertakes a procedure for controlling the radio access bearers based on the traffic volume measurement of the channel CCTrCH provided thereto. The procedure for controlling the radio access bearers has been explained already.

As has been explained, the method for active control of a radio access bearer in a mobile communication system of the present invention has the following advantages.

A procedure for controlling radio access bearers is provided in more detail over the traffic volume monitoring. Therefore, establishment, sustenance, and cancelation of radio resource access can be carried out efficiently in the radio interface protocol architecture according to traffic volumes of the RLC and MAC, which are sub-layers of the second layer.

And, the functions of establishment, sustenance, and cancelation of the radio access bearers and the radio resources required for radio resource access can be carried out more efficiently.

It will be apparent to those skilled in the art that various modifications and variations can be made in the method for controlling a radio access bearer in a mobile communication system of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. 

What is claimed is:
 1. A method for controlling a radio access bearer in a mobile communication system, comprising the steps of: (1) disposing a radio resource control layer having radio access bearers in a user side of the communication system; (2) disposing a radio link control layer, a media access control layer, and a physical layer in the user side beneath the radio resource control layer in succession; (3) measuring traffic volumes of the media access control layer and radio link control layer in the user side by checking the traffic volume of a transport channel under the media access control layer in the user side to produce traffic volume measurements; (4) comparing the traffic volume measurements to at least one of an upper critical value or a lower critical value provide to the media access control layer in the user side from a radio resource control layer in a network side of the communication system through the radio resource control layer in the user side of the system, and forwarding a comparison result and the traffic volume measurements to the radio resource control layer in the network side through the radio resource control layer in the user side; and, (5) controlling the radio access bearers in the user side through the radio resource control layer in the network side according to a result of the comparison.
 2. A method as claimed in claim 1, wherein traffic volume comprises a sum of data at buffers of all transport channels and all data existing at buffers of all logical channels, both being multiplexed into a coded composite transport channel.
 3. A method as claimed in claim 1, wherein the upper and lower critical values may be varied as the steps (3) and (4) are repeated.
 4. A method as claimed in claim 3, wherein, if the varied lower critical value drops below a particular level, a transport channel can be switched from a first transport channel type to a second transport channel type.
 5. A method as claimed in claim 4, wherein the first transport channel type is a dedicated channel, and the second transport channel type is a random access channel.
 6. A method as claimed in claim 1, wherein the step (5) includes the step of correcting a configuration of the physical layer channels according to the comparison result.
 7. A method as claimed in claim 1, wherein the step (2) includes the step of the radio resource control layer in the user side transporting a disposal request primitive to the media access control layer, the disposal request primitive having a radio access bearer ID, a logical channel ID which is multiplex information, a transport channel ID, and information on a logical channel priority dependent on a service quality, and a transport format combination set which is channel information.
 8. A method as claimed in claim 1, further comprising the radio resource control layer in the network side transporting a system information message through a broadcasting control channel, and a measurement control message through a dedicated control channel, to the radio resource control layer in the user side, for providing the radio resource control layer in the user side with parameters required for the traffic volume measurements before the step (3).
 9. A method as claimed in claim 8, further comprising the step of the radio resource control layer in the user side transporting a primitive for requesting monitoring of the traffic volume to the media access control layer in the user side after reception of all the parameters, the primitive having a measurement report mode parameter identifying a measurement report mode, and a measurement period parameter.
 10. A method as claimed in claim 9, wherein the primitive further includes a report interval parameter when the measurement report mode is a periodic mode, and an upper critical value and a lower critical value when the measurement report mode is an event trigger mode.
 11. A method as claimed in claim 10, wherein the upper critical value represents a greatest boundary traffic volume, and the lower critical value represents a smallest boundary traffic volume, both for the media access control layer in the user side to report the traffic volume measurements.
 12. A method as claimed in claim 9, wherein, when the present measurement report mode is a periodic mode, the media access control layer transports measurement results at transport buffers in the radio link control layer and measurement results of its own transport buffers to the radio resource layer in the user side periodically, and conversely, when the present measurement report mode is an event trigger mode, the media access control layer in the user side compares a sum of measurement results at the transport buffers in the radio link control layer and measurement results at its own transport buffers to the upper critical value and the lower critical value, and reports the comparison result to the radio resource control layer in the user side.
 13. A method as claimed in claim 1, wherein a primitive is used when the media access control layer in the user side reports the traffic volume measurements, and a total amount of data existing at transport buffers in the radio link control layer and transport buffers in the media access control layer is used as a parameter.
 14. A method as claimed in claim 13, wherein totals, an average, and deviations of data existing at buffers of respective radio access bearers are used as other parameters.
 15. A method as claimed in claim 13, wherein traffic volumes transported on respective transport channels, averages and deviations which are statistics of the traffic volumes are used as other parameters.
 16. A method as claimed in claim 1, wherein the radio resource control layer in the user side receives the traffic volume measurements and the comparison result from the media access control layer in the user side, and transports the traffic volume measurements and the comparison result to the radio resource control layer in the network side by using the primitive through a dedicated control channel.
 17. A method as claimed in claim 1, wherein controlling the radio access bearer includes: bearer reconfiguration in which all configurations of the radio link control layer, media access control layer, and physical layer in the user side are revised; transport channel reconfiguration in which media access control layer configurations and physical layer configurations are revised; and physical channel reconfiguration in which a configuration of the physical layer in the user side is revised.
 18. A method for controlling radio bearers in a mobile radio communication device having a radio resource control layer and having a radio link control layer, a media access control layer, and a physical layer beneath the radio resource control layer in succession, comprising: measuring traffic volume of a transport channel between said media access control layer and said physical layer in said media access control layer; comparing the measured traffic volume with an upper threshold and a lower threshold provided from said radio resource control layer; reporting the measured traffic volume to said radio resource control layer by said media access control layer when said measured traffic volume is not in the range between said upper threshold and lower threshold; and controlling the radio bearers by said radio resource control layer according to the report.
 19. A method as claimed in claim 18, wherein the traffic volume is a sum of data at buffers mapped to a transport channel.
 20. A method as claimed in claim 18, wherein the traffic volume is a sum of all transport channels which are multiplexed into a code composite transport channel.
 21. A method as claimed in claim 18, wherein said controlling step includes the reconfiguration of the radio bearers and reconfiguration of the transport channel.
 22. A method as claimed in claim 18, wherein the mobile radio communication device is a mobile terminal and the upper threshold and lower threshold are provided to said radio resource control layer from the radio resource control layer of a UTRAN which is communicating with said mobile terminal.
 23. A method as claimed in claim 22, wherein the reporting is relayed to the radio resource control layer of the UTRAN, and the controlling is made by the radio resource control layer of the UTRAN.
 24. A method as claimed in claim 18, further including reporting the average and variance which are statistics of the traffic volume. 